Airplane fabric attachment



Dec. 20, 1938'. K. SCHMIDT 2,140,558

AIRPLANE FABRIC ATTACHMENT Filed June 3, 1938 E 20'/ E /7 5//4 l5 /3 /0 l0 j /l I Il mvENToR KARL `SCHMIDT v APatented Dec. `*20, 1938 UNITEDl STATES PATENT oFFlcE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. '157) The present invention relates to airplane fabric attachments and it has a particular `relation to the cap-strips of the wing structure to which the fabric is secured.

One of the objects of the present invention is Another object of the invention is the provision of a fastening means for aircraft fabric in which the full strength of the fabric is developed when `abnormal air-loads are imposed thereon. l With these and other objects in view, as well as other advantages that may be incident to the use ofthe improvements, the invention consists in the parts and combinations thereof hereinafter set forth and claimed, with the understanding that the several necessary elements constituting the same may be varied in proportion Vand arrangement without departing from the nature and scope of the invention, as defined in the appended claim.

s In order to make the invention more clearly understood, there is shown inthe accompanying drawing, means for carrying the invention into practical use, withoutlimlting the improvements in their useful applicationto the particular construction. which, for the purpose of explanation,

have been the subject of illustration.

In the accompanying drawing: Fig. 1 is a transverse sectional view through a cap-strip and fabric attaching means constructed in accordance with the invention; and

Fig. 2 is a fragmentary side elevational view on a reduced scale of the cap-strip structure shown in Fig. 1.

Referring to the drawing, a cap-strip of an airplane rib structure is shown as comprising two Il, the vertical complementary angle strips flanges VIi of which are secured together by rivets I2 and offset at il to provide a space I4 and the vhorizontal flanges Il of which extend in opposite 5 directions to provide a supporting surface for the e load fabric IB. When the fabric is secured to the capfstrip it is tucked down into the space Il by means of a load-strip I1 having a rounded lower t edge which is forced into the space along with the f fabric and secured in position by means of keeper-pins Il provided with heads il. vThese pins extend horizontally through the flanges il of the cap-strip, reenforcing angle members 2l, the fabric Il and the load-strip I1 and are formed with pointed extremities 2| to pierce the fabric between the threads withoutunduly rupturing the same. The pins Il are themselves maintained against displacement by washers 22 and a single locking wire 22 which is threaded through holes. 5 in a series of pins adjacent to the washers and which preferably extends the full length of the cap-strip. A length of tape 24 is cemented to' the fabric covering over the depression formed where the fabric is tucked into the space il so 1o as to provide a smooth flush surface.

It will be apparent from the foregoing that the entire lift load in the plane of the rib is transmitted to the spaced keeper-pins by means of the load-strip Il which functions as a continuous l5 beam: that the lift load e'xerts a shearing reaction on the keeper-pins instead of placing them under tension, as in former structures; that the flanges of the cap-strip are relatively wide to resist bending action and consequent separation of 20 the two halves ofthe cap-strip between the keeper-pins: and that there is no necessity of having the keeper-pins fit tightly as they are always under shear loading.

It will be understood that the above description 25 and accompanying drawing comprehend only the general and preferred embodiment of the invention, and that various other changes in the construction, proportion, and arrangement of the parts may be made by those skilled in thev art without departing from the nature and scope of the invention as defined in the appended claim.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having described my invention, I claim: IAttachment for aircraft'fabric covering comprising a cap-strip formed of two complementary 5 angle members secured togetherand having a space therebetween into which thefabric extends. a load-strip disposed within saidspace and over the fabric therein, the outer edge of said `loadstrip being disposed within the plane of said covv55 ering to provide a smooth unbroken surface. and fastening pins extending transversely through said cap-strip, fabric and load-strip and disposed parallel to the plane of said covering for secur- 'ing the fabric and load-strip in said space, said 50 mns being thus subjected to shearing strains only when the covering is air-loaded.

KARL SCHMIDT. 

